Carry cart

Abstract

A handle shaft (30) of a carry cart (CC) coupled to a loading platform (20) by a coupling part (29) has a center axis (CL1) that extends obliquely. A front wheel (32) of the carry cart (CC) is supported by the handle shaft (30) via a link member (37) and an arm (41) respectively provided below the coupling part (29). An arm body part (42) of the arm (41) is supported by a link shaft (40) to the rear of a front wheel axle (33) so as to be rotatable in the vertical direction with respect to a link body part (39) of the link member (37). An elastic part (55) that is elastically deformed accompanying the upward rotation of the arm (41) is disposed to the rear of the arm (41). In a state in which the front wheel (32) and a rear wheel (34) are in contact with a horizontal surface, the link shaft (40) is located to the rear of the center axis (CL1) and below the coupling part (29).

Description

Carry cart

[0001] The present disclosure relates to a carry cart having wheels that rotate about axles to roll on a road surface. The carry cart moves by the rolling of the wheels.

[0002] In the field of carry carts, various structures have been proposed for enabling wheels to overcome convex steps. For example, a walking aid described in Patent Document 1 is provided with main wheels corresponding to the front wheels, and auxiliary wheels are provided in front of the main wheels in the direction of travel. The contact surfaces of the auxiliary wheels are set above the contact surfaces of the main wheels. A link mechanism is interposed between the auxiliary wheels and the main wheels. When the main wheels contact a step, they are moved rearward and upward in the direction of travel. This movement reduces the impact when the main wheels contact the step. This movement of the main wheels is transmitted to the auxiliary wheels via the link mechanism, causing the auxiliary wheels to pivot downward. As a result, the auxiliary wheels contact the top surface of the step and press down on the top surface, preventing the walking aid from tipping forward.

[0003] When the main wheels overcome the step, the auxiliary wheels are rotated upward by the elastic bodies and return to their original positions, returning the walking aid to the same posture as before the step was overcome.

[0004] Japanese Patent Application Laid-Open No. 2006-306246

[0005] The technology described in Patent Document 1 requires training wheels to enable the main wheels, which correspond to the front wheels, to overcome steps. However, there is a demand for a carry cart that allows the front wheels to overcome steps without using such training wheels.

[0006] A carry cart according to one aspect of the present disclosure includes wheels configured to roll on a road surface, a loading platform located above the contact points of the wheels with the road surface, a handle shaft having a central axis extending in a direction intersecting a horizontal plane and connected to the loading platform by a connecting portion, and a link member and an arm respectively provided below the connecting portion. The wheels include front wheels supported on the handle shaft via the link member and the arm and configured to roll by rotating around a front axle, and rear wheels configured to roll behind the front wheels in the direction of travel of the carry cart. The carry cart is configured to travel forward in the direction of travel by the rolling of each wheel. The link member is attached to the handle shaft and has a link main body portion behind the front axle in the direction of travel. The arm supports the front axle, and the arm has an arm main body portion behind the front axle in the direction of travel and supported by the link shaft so as to be rotatable up and down relative to the link main body portion. An elastic part configured to be elastically deformed as the arm rotates upward around the link shaft is disposed behind the arm in the traveling direction. When the front wheel and the rear wheel are both in contact with the same horizontal plane, the link shaft is located behind the central axis and below the connecting part.

[0007] FIG. 1 is a partial side cross-sectional view of a support mechanism for a front wheel in one embodiment of a carry cart. FIG. 2 is a side view of the carry cart in the embodiment shown in FIG. 1, in which the front wheel contacts the rear corner of a step. FIG. 3 is a perspective view of the carry cart in the embodiment shown in FIG. 1. FIG. 4 is a bottom view of the carry cart in the embodiment shown in FIG. 1. FIG. 5 is a partial perspective view showing an enlarged view of the support mechanism in FIG. 3. FIG. 6 is an exploded perspective view showing the components of the support mechanism in FIG. 3. FIG. 7 is a partial side view showing an enlarged view of the support mechanism in FIG. 2. FIG. 8 is a partial side view of the carry cart in the embodiment shown in FIG. 1, in which the front wheel is being lifted. FIG. 9 is a partial side view of the carry cart in the embodiment shown in FIG. 1, in which the front wheel rolls on the top surface of a step. FIG. 10 is a diagram illustrating the amount of sinking of the link member (the amount of downward movement of the link shaft) when the front wheel contacts the corner of a step in the embodiment shown in FIG. 1.

[0008] An embodiment of a carry cart will be described below with reference to the drawings. As shown in Figure 2, the carry cart CC includes a plurality of wheels for rolling on a road surface 10, a loading platform 20 on which a transported object C1 such as luggage is placed, and a handle shaft 30 connected to the loading platform 20 and gripped and operated by a user of the carry cart CC.

[0009] The carry cart CC moves forward in the direction of travel by the rotation of each wheel. In Figures 1, 2, 4, 7 to 9, the direction of travel is from right to left in each figure, and the front in the direction of travel is the left side in each figure.

[0010] In the following description, the forward direction of the carry cart CC is referred to as the front, and the backward direction is referred to as the rear. The up-down direction refers to the vertical direction of the carry cart CC, and the left-right direction refers to the direction perpendicular to both the forward direction and the up-down direction. The left-right direction refers to the width direction of the carry cart CC, and coincides with the left-right direction when the carry cart CC is moving forward.

[0011] <Road surface 10> The road surface 10 on which the carry cart CC travels has a convex step 12. In order to distinguish the convex step 12 from portions of the road surface 10 that are not the step 12, the latter will be referred to as a general road surface 11. The upper surface of the step 12 will be referred to as a top surface 13, and the upper rear corner of the step 12 will be referred to as a rear corner 14. For ease of explanation, it is assumed here that both the general road surface 11 and the top surface 13 are horizontal surfaces.

[0012] The top surface 13 is, for example, the upper surface of a sidewalk. The general road surface 11 is, for example, the upper surface of a roadway. Next, each part of the carry cart CC will be described.

[0013] <Loading Platform 20> As shown in Figures 2 to 4, the loading platform 20 includes a loading platform main body 21 and an attachment protrusion 23. The loading platform main body 21 is box-shaped with one end closed. The loading platform main body 21 is provided with a storage section 22 having an opening 22a at its upper end. The transported object C1 can be placed in and removed from the storage section 22 through the opening 22a. The attachment protrusion 23 is provided on the upper part of the loading platform main body 21, at least in a position adjacent to and in front of the opening 22a. In this embodiment, the attachment protrusions 23 are provided in addition to the above positions on the upper part of the loading platform main body 21, adjacent to both the left and right sides of the opening 22a.

[0014] Rear wheel support portions 24 are fixed to the left and right sides of the bed body 21. The rear wheel support portions 24 are spaced apart from each other in the left-right direction. As shown in Figures 2 and 4, the lower portions of the rear wheel support portions 24 extend downward below the bottom surface 21a of the bed body 21.

[0015] As shown in Figures 1, 3, and 5, a bearing portion 25 is fixed to the mounting protrusion 23 in a portion forward of the opening 22a and in the center of the loading platform 20 in the left-right direction. The bearing portion 25 includes two bearing plates 26 and a connecting plate 27. When the front wheels 32 and the rear wheels 34 are both in contact with the same horizontal plane, the two bearing plates 26 are inclined relative to the horizontal plane so that the front ends are positioned higher. The connecting plate 27 is inclined relative to the vertical plane so that the upper ends are positioned further rearward. The connecting plate 27 connects the rear edges of the two bearing plates 26 together. The connecting plate 27 is fastened to the mounting protrusion 23 by fastening members 28 such as bolts and nuts.

[0016] <Steering Wheel Shaft 30> As shown in Figure 2, the steering wheel shaft 30 has a central axis CL1 that extends in a direction intersecting a horizontal plane. In this embodiment, the central axis CL1 is inclined with respect to the vertical line VL so that the central axis CL1 is positioned more rearward as it approaches the upper side. The angle that the central axis CL1 forms with the vertical line VL is referred to as the caster angle θ1. In this embodiment, the caster angle θ1 is set to 20° as an example, but is not limited to this.

[0017] 1 and 5, the lower portion of the handle shaft 30 is inserted through the two bearing plates 26. The lower end of the handle shaft 30 protrudes downward from the lower of the two bearing plates 26. The handle shaft 30 is supported by the bearings 25 at both bearing plates 26. The handle shaft 30 constitutes a steering shaft and is capable of rotating about a central axis line CL1.

[0018] The handle shaft 30 is connected to the front upper end of the cargo bed 20 by a fastening member 28 via a bearing portion 25. The portion where the handle shaft 30 is connected to the cargo bed 20 by the fastening member 28, more specifically, the portion where the fastening member 28 is inserted in the connecting plate portion 27, is sometimes referred to as a connecting portion 29 of the handle shaft 30 to the cargo bed 20.

[0019] 2, the carry cart CC has a grip 31 attached to the upper end of a handle shaft 30 and gripped by a user of the carry cart CC. By changing the orientation of the grip 31, the user can rotate the handle shaft 30 around the central axis CL1.

[0020] <Plural Wheels> As shown in FIGS. 2 and 4, the plural wheels include a single front wheel 32 and two rear wheels 34.

[0021] The front wheels 32 are supported on the handle shaft 30 by a support mechanism M1 provided below the connecting portion 29. The front wheels 32 are drive wheels that are driven to rotate about the front wheel axles 33 by a motor (not shown) serving as a power source, thereby providing the propulsive force for traveling to the carry cart CC. The motor receives power from a battery (not shown) mounted on the loading platform 20 or the like. The motor may be, for example, a so-called in-wheel motor, which is an electric motor disposed inside or near the front wheels 32 and transmits power to the front wheels 32 to directly drive and rotate the front wheels 32. In this embodiment, the front wheels 32 use the in-wheel motor.

[0022] 5 and 6, the front wheels 32 and the front axles 33 are configured as an integral part. Both ends of the front axles 33 protrude from the front wheels 32 on either side in the direction in which the front axles 33 extend.

[0023] As shown in Figures 2 to 4, the rear wheel axle 35 of each rear wheel 34 is rotatably supported by a portion of the rear wheel support part 24 that is below the bottom surface 21a of the bed main body part 21. This allows each rear wheel 34 to rotate relative to the rear wheel support part 24. Each rear wheel 34 rolls on the road surface 10 by rotating around the rear wheel axle 35. Unlike the front wheels 32, both rear wheels 34 are driven wheels that do not generate driving force. Both rear wheels 34 have a wheel diameter (diameter) that is approximately the same as that of the front wheels 32.

[0024] 2 and 4, the cargo bed 20 is disposed above the contact points of the front wheels 32 and rear wheels 34 with the road surface 10, for example, the general road surface 11. The bottom surface 21a of the cargo bed 20 is located higher than the lowermost ends of the front wheels 32 and rear wheels 34 and lower than the uppermost ends of the wheels.

[0025] The support mechanism M1 includes a link member 37, an arm 41, a bracket 51, and an elastic portion 55. <Link member 37> As shown in Figures 1 and 5, as described above, the lower end of the handle shaft 30 protrudes downward beyond the lower of the two bearing plate portions 26. The link member 37 is fastened to the lower end of the handle shaft 30 by a fastening member 38 such as a bolt so as to be rotatable integrally therewith.

[0026] 5 and 6, the link member 37 has two link main bodies 39 each extending in the vertical direction. The two link main bodies 39 are disposed rearward of the front wheel axle 33. The two link main bodies 39 are spaced apart from each other in the direction in which the front wheel axle 33 extends. The distance between the two link main bodies 39 is slightly larger than the dimension of the front wheel 32 in the direction in which the front wheel axle 33 extends.

[0027] <Arm 41> The arm 41 includes two arm main bodies 42 and an arm attachment portion 46. Each arm main body 42 includes a front plate portion 43 and a rear plate portion 45 adjacent to the rear side of the front plate portion 43. The two arm main bodies 42 are disposed on either side of the front wheel 32 in the direction in which the front wheel axle 33 extends.

[0028] 2, 6, and 7, when the front wheels 32 and both rear wheels 34 are in contact with a horizontal surface, such as the general road surface 11, the front plate portion 43 of each arm main body 42 is inclined relative to the general road surface 11 so that the front is positioned lower. The rear plate portion 45 of each arm main body 42 extends in the front-to-rear direction. In each arm main body 42, the front plate portion 43 is bent relative to the rear plate portion 45 so as to form a protrusion that protrudes diagonally forward and upward.

[0029] The arms 41 support the front wheel axles 33. As a result, the front wheels 32 are supported by the link members 37. More specifically, each front plate 43 has a notch 44 formed therein that extends diagonally upward and rearward from the front lower end of the front plate 43 when both the front wheels 32 and the rear wheels 34 are in contact with the same horizontal plane. That is, the notch 44 of each front plate 43 is inclined with respect to the horizontal and vertical planes so that the more rearward the notch 44 is positioned, the higher it is. The portion of the front wheel axle 33 that protrudes from the front wheels 32 is inserted into and supported by the notch 44 of each front plate 43. The arm attachment portion 46 connects the rear edges of the two arm main bodies 42 rearward of the front wheels 32.

[0030] The arm 41 configured as described above is disposed between the two link main bodies 39. More specifically, each arm main body 42 is disposed adjacent to the inside of the corresponding link main body 39 in the direction in which the front wheel axle 33 extends.

[0031] Each arm body 42 is supported by a link shaft 40 rearward of the front wheels 32 so as to be rotatable in the vertical direction relative to the adjacent link body 39 on the outer side in the direction in which the front wheel axle 33 extends.

[0032] <Bracket 51> As shown in Figures 1, 2, and 6, the bracket 51 includes a flat bracket main body 52 and two mounting plates 53. Each mounting plate 53 is adjacent to the outer side of the corresponding link main body 39 in the direction in which the front wheel axle 33 extends (see Figure 5). The bracket main body 52 is located rearward of the two link main bodies 39 and rearward of the arm mounting portion 46. The bracket main body 52 connects the rear edges of the two mounting plates 53 to each other. Each mounting plate 53 is fastened to the adjacent link main body 39 on the inner side in the direction in which the front wheel axle 33 extends by a fastening member 54 such as a bolt. Each mounting plate 53 is connected to the adjacent link main body 39 by a link shaft 40.

[0033] 1 and 6 , the elastic portion 55 includes an elastic main body portion 56, a first attachment portion 57, and a second attachment portion 58. The elastic portion 55 is disposed between the arm attachment portion 46 and the bracket main body portion 52.

[0034] The elastic main body 56 is made of rubber and is elastically deformable. The elastic main body 56 has a central axis CL2. The elastic main body 56 is bowl-shaped with an open rear surface. The outer surface of the elastic main body 56 has a hemispherical curved surface 56a that curves to bulge forward. The inner surface of the elastic main body 56 has a hemispherical curved surface 56b that curves to concave forward.

[0035] The first and second covering portions 57 and 58 are formed from a material that is less susceptible to elastic deformation than the elastic main body portion 56, such as metal. The first and second covering portions 57 and 58 have greater strength than the elastic main body portion 56. The first and second covering portions 57 and 58 are attached to the front end of the elastic main body portion 56, and the second covering portion 58 is attached to the rear end of the elastic main body portion 56. In other words, the first and second covering portions 57 and 58 are connected to each other by the elastic main body portion 56.

[0036] The first attachment portion 57 of the elastic portion 55 is fastened to the arm attachment portion 46 by a fastening member 61 such as a bolt. The second attachment portion 58 of the elastic portion 55 is fastened to the bracket main body 52 by a fastening member 62 such as a bolt.

[0037] The elastic main body 56 of the elastic portion 55 configured in this manner is compressed and elastically deformed as the arm 41 rotates upward about the link shaft 40. In this embodiment, as shown in Figures 2 and 7, with the front wheel 32 and the rear wheel 34 both in contact with the same horizontal plane, the link shaft 40 is located rearward of the center axis CL1 of the handle shaft 30 and below the connecting portion 29.

[0038] The front wheels 32 are supported on the handle shaft 30 by a support mechanism M1. Therefore, when the handle shaft 30 is rotated about the central axis CL1 in response to the operation of the grip 31, the direction in which the front wheel axle 33 extends is changed in response to the rotation. By turning the front wheels 32, the traveling direction of the carry cart CC is changed.

[0039] <Operation of this embodiment> In describing the operation of this embodiment, it is assumed that the load C1 is placed on the platform 20 of the carry cart CC as shown in FIG.

[0040] When the front wheel 32 and both rear wheels 34 contact the general road surface 11, which is a horizontal plane, the bottom surface 21a of the carrier 20 is in a horizontal state. As shown by arrow A in Figure 2, when the front wheel 32 is rotated forward by the motor, a propulsive force is generated in the front wheel 32 for moving the carry cart CC forward. This propulsive force is transmitted to the rear wheels 34 via the arm 41, link member 37, handle shaft 30, carrier 20, etc. The rear wheels 34 are pulled forward by the transmitted propulsive force and rotate forward in conjunction with the front wheels 32, as shown by arrow B.

[0041] The front wheels 32 and both rear wheels 34 roll forward on the general road surface 11. The carry cart CC travels (self-propels) forward along the general road surface 11 without tilting the bottom surface 21a. As shown in FIGS. 1 and 7 , as the carry cart CC travels (self-propels), the front wheels 32 contact the rear corner 14 of the step 12 from behind. This contact causes a force from the front wheels 32 to act diagonally forward and downward on the step 12. In particular, since a transported object C1 is loaded on the loading platform 20, when the front wheels 32 contact the step 12 and restrict the forward travel of the carry cart CC, the transported object C1 tends to move forward due to inertia. Therefore, the diagonally forward and downward force is more likely to act on the corner 14 from the front wheels 32. Meanwhile, as a reaction force to the above force, a reaction force RF1 acts on the front wheels 32 from the corner 14 in a diagonally upward and rearward direction. This reaction force RF1 is a force that tries to push back the front wheel 32 that is trying to move forward.

[0042] If the carry cart CC is not designed to make it easier for the front wheels 32 to climb over the step 12, it will be difficult for the front wheels 32 to climb over the step 12. As the step 12 becomes higher, it becomes more difficult for the front wheels 32 to climb over the step 12.

[0043] In this regard, in this embodiment, the arm 41 is supported by the link shaft 40 so as to be rotatable in the vertical direction relative to the link member 37. The reaction force RF1 causes the arm 41 to attempt to rotate upward about the link shaft 40 while compressing and elastically deforming the elastic portion 55 rearward and downward. As a result, an upward force F1 acts on the front wheel 32.

[0044] When the front wheel 32 rotating forward comes into contact with the corner 14 of the step 12, a force acting diagonally downward and rearward acts from the front wheel 32 on the corner 14. As shown in Figure 8, a reaction force RF2 of this force acts from the corner 14 on the front wheel 32. As components of this reaction force RF2, an upward component force Fa and a forward component force Fb act on the front wheel 32.

[0045] The component force Fa is added to the upward force F1 acting on the front wheels 32 as the arms 41 rotate, lifting the front wheels 32. Meanwhile, the rear wheels 34 are still in contact with the general road surface 11. Therefore, as shown in Figure 8, the bottom surface 21a of the loading platform 20 is tilted relative to the horizontal plane so that it becomes lower towards the rear.

[0046] Here, the dimension from the lowest point of the front wheel 32 that has been lifted as described above to the top surface 13 of the step 12 is defined as the overlap (lap) Δh. As the wheel is lifted as described above, the overlap Δh decreases. As the overlap Δh decreases, the force required for the front wheel 32 to climb over the step 12 decreases. Therefore, unlike conventional carry carts, the front wheel 32 can easily climb over the step 12 without using training wheels.

[0047] 9, when the front wheel 32 runs over the step 12, that is, when the front wheel 32 passes the corner 14, the reaction force RF1 (see FIGS. 1 and 7) no longer acts on the front wheel 32. Due to the elastic restoring force of the elastic portion 55, the arm 41 rotates downward about the link shaft 40 as shown by arrow C in FIG. 9, and the front wheel 32 returns to the same state as before it ran over the step 12.

[0048] When the front wheels 32 climb up onto the step 12, the front wheels 32 contact the top surface 13 of the step 12, and both rear wheels 34 remain in contact with the general road surface 11. The front wheels 32 are positioned higher than the rear wheels 34. The bottom surface 21a of the loading platform 20 remains inclined relative to the horizontal plane so that it becomes lower towards the rear.

[0049] When the front wheel 32 rotates forward as indicated by arrow A and both rear wheels 34 rotate forward as indicated by arrow B, the carry cart CC, with the bottom surface 21a of the loading platform 20 tilted relative to the horizontal plane as described above, travels forward. As the carry cart CC travels, both rear wheels 34 come into contact with the rear corners 14 of the step 12 from behind, although this is not shown. As shown in FIG. 2 , when the front wheel 32 contacts the corners 14 of the step 12, the bottom surface 21a of the loading platform 20 is not tilted relative to the horizontal plane. In contrast, when both rear wheels 34 contact the corners 14, the bottom surface 21a of the loading platform 20 is tilted relative to the horizontal plane so that it is lower toward the rear. Therefore, when both rear wheels 34 contact the corners 14, a force acts on the rear wheels 34 obliquely forward and upward, unlike when the front wheels 32 contact the step 12.

[0050] Therefore, both rear wheels 34 can go over the step 12 with less force than when the front wheel 32 goes over the step 12. Furthermore, a force pulling both rear wheels 34 forward acts on both rear wheels 34 due to the propulsive force generated by the rotational driving of the front wheel 32. This force causes both rear wheels 34 to rotate forward as shown by arrow B in Figure 9, and when they go over the step 12, both the front wheel 32 and both rear wheels 34 come into contact with the top surface 13 of the step 12, although this is not shown.

[0051] When the front wheel 32 comes into contact with a new convex step while the carry cart CC continues to travel on the top surface 13, the front wheel 32 and both rear wheels 34 go over the new step in the same way as when going over the step 12 from the general road surface 11.

[0052] As shown in Figures 1 and 7, when the front wheel 32 of the carry cart CC makes contact with the rear corner 14 of the step 12 from behind while the carry cart CC is traveling (self-propelled), the handle shaft 30 attempts to rotate in the direction indicated by arrow D, with the connecting portion 29 as the fulcrum. This causes the link member 37 to sink, and the link shaft 40 to move downward. Meanwhile, the vertical position of the front wheel axle 33 remains unchanged. Therefore, the arm 41 rotates upward about the link shaft 40, compressing and elastically deforming the elastic portion 55. The amount of this elastic deformation increases as the sinking amount S of the link member 37 increases. Due to this elastic deformation, the amount of elastic deformation of the elastic portion 55 that can be used to lift the front wheel 32 when climbing over a step is reduced.

[0053] 10 , when the handle shaft 30 rotates a certain angle θ3 around the connecting portion 29 as a fulcrum, the amount of depression S of the link member 37 and the amount of downward movement of the link shaft 40 vary depending on the position of the link shaft 40 before rotation. For example, when the link shaft 40 is located rearward of the center axis CL1 of the handle shaft 30, which is inclined so that the upper part is positioned rearward as described above, the amount of depression S of the link member 37 is smaller than the amount of depression S when the link shaft 40 is located forward of the center axis CL1. The same applies to the amount of downward movement of the link shaft 40. When the link shaft 40 is located rearward of the center axis CL1, the amount of depression S and the amount of movement decrease as the link shaft 40 approaches the position directly below the connecting portion 29.

[0054] 1 and 7, in this embodiment, the link shaft 40 is located rearward of the center axis CL1 of the handle shaft 30 and below the connecting portion 29. Therefore, the amount of sinking S of the link member 37 is small when the front wheel 32 comes into contact with the corner 14 of the step 12 (see FIG. 10). Also, the amount of downward movement of the link shaft 40 is small when the front wheel 32 comes into contact with the corner 14 of the step 12.

[0055] As shown in FIG. 7 , the length between the link shaft 40 and the connecting portion 29 is defined as the link shaft connecting portion distance L1. The angle between the imaginary line IL passing through the link shaft 40 and the connecting portion 29 and the vertical line VL is defined as the link shaft connecting portion angle θ2. The position of the link shaft 40, in this case the vertical position of the link shaft 40 when the general road surface 11 is used as the reference, is defined as the link shaft position P. In other words, the height of the link shaft 40 from the general road surface 11 is defined as the link shaft position P. FIG. 10 shows the sinking amount S of the link member 37 when the handle shaft 30 is rotated a certain angle θ3, for example, 3 degrees, around the connecting portion 29 as a fulcrum. The angle is measured in degrees.

[0056] Four combinations were set for the multiple caster angles θ1, multiple link shaft coupling distances L1, multiple link shaft coupling angles θ2, and multiple link shaft positions P shown in Figures 2 and 7. The four combinations included three examples (Examples 1 to 3) and a comparative example. For each combination, the sinking amount S of the link member 37 shown in Figure 10 was calculated. The results are shown in Table 1.

[0057]

[0058] In Examples 1 to 3, the link shaft 40 is disposed rearward of the center axis CL1 and below the connecting portion 29. In Examples 1 to 3, the link shaft connecting portion distance L1 is set to a common value of 153.66 mm. In Examples 1 to 3, the caster angle θ1, the link shaft connecting portion angle θ2, and the link shaft position P are each set to different values ​​for each example.

[0059] In Table 1, "Initial" indicates the value before the front wheel 32 comes into contact with the corner 14. In Table 1, "After rotation" indicates the value after the front wheel 32 comes into contact with the corner 14, causing the handle shaft 30 to rotate by an angle θ3 (3 degrees in this case) in the direction indicated by arrow D, with the connecting portion 29 as the fulcrum.

[0060] In the comparative example, the link shaft 40 is positioned forward of the center axis CL1, and the caster angle θ1 is set to 0 degrees. Table 1 shows that the sinking amount S of the link member 37 is −3.582 mm in the comparative example, whereas it is −0.337 mm to −1.727 mm in Examples 1 to 3, which is less than that in the comparative example.

[0061] As described above, when the sinking amount S of the link member 37 is small and the downward movement amount of the link shaft 40 is small, the upward rotation amount of the arm 41 around the link shaft 40 is small. Therefore, the compressive elastic deformation amount of the elastic portion 55 is small, and the amount of elastic deformation that can be used by the elastic portion 55 to lift the front wheel 32 when going over a step is increased accordingly.

[0062] 1, a link member 37 is attached to the handle shaft 30. An arm 41 that supports the front wheel axle 33 is supported by the link shaft 40 so as to be rotatable in the vertical direction relative to the link member 37. An elastic portion 55 is disposed behind the arm 41, which is compressed and elastically deformed as the arm 41 rotates upward around the link shaft 40.

[0063] Therefore, when the front wheel 32 comes into contact with the corner 14 of the step 12, a reaction force RF1 acting diagonally upward and rearward is applied to the front wheel 32 from the corner 14, causing compressive elastic deformation of the elastic main body 56 of the elastic part 55, thereby rotating the arm 41 upward. As a result, an upward force F1 can be applied to the front wheel 32.

[0064] 8, when the front wheel 32 rotating forward comes into contact with the corner 14, a reaction force RF2 acting obliquely upward and forward acts on the front wheel 32 from the corner 14. An upward component force Fa of this reaction force RF2 can be applied to the front wheel 32.

[0065] By lifting the front wheel 32 with the force F1 and the component force Fa and reducing the engagement allowance Δh, it is possible to reduce the force required to make the front wheel 32 go over the step 12. As a result, the front wheel 32 can go over the step 12 without using training wheels.

[0066] (2) In the case of a non-self-propelled carry cart that is pushed forward by the user, when the front wheels come into contact with a convex step 12 and are prevented from moving, the user lifts the front wheels of the carry cart. This operation allows the front wheels to climb over the step.

[0067] In contrast, in a self-propelled carry cart, the user does not need to lift the front wheel as described above. In this regard, in this embodiment, the front wheel 32 is a drive wheel that is driven by a motor and provides the propulsive force for the carry cart CC to travel. For a carry cart CC in which the front wheel 32 is a drive wheel, the above-mentioned configuration (1) is adopted. That is, the carry cart CC includes a link member 37, an arm 41, and an elastic portion 55.

[0068] Therefore, although the carry cart CC is a self-propelled carry cart that is not operated by the user, the front wheels 32 can be made to climb over the step 12. Therefore, the above configuration (1) is particularly useful for the carry cart CC of this embodiment, which does not have any means for making the front wheels 32 climb over the step 12 other than by making the front wheels 32 climb over the step 12 using the driving force of the front wheels 32.

[0069] (3) As shown in Figures 2 and 7, with both the front wheel 32 and the rear wheel 34 in contact with the road surface 10, which is the same horizontal plane, the link shaft 40 is positioned rearward of the center axis CL1 of the handle shaft 30 and below the connecting portion 29.

[0070] Therefore, the amount of sinking S of the link member 37 when the front wheel 32 comes into contact with the corner 14 of the step 12 can be reduced, thereby reducing the amount of elastic deformation of the elastic portion 55 when the front wheel 32 comes into contact with the step. Therefore, the elastic deformation of the elastic portion 55 can be effectively used to move the front wheel 32 over the step.

[0071] 1 and 2, the center axis CL1 of the handle shaft 30 is inclined relative to the vertical line VL so that the upper part is positioned further rearward. Therefore, when a load is applied to the grip portion 31, the load can be prevented from being transmitted to the elastic portion 55 via the handle shaft 30, the link member 37, etc.

[0072] 1 and 6, the outer surface of the elastic body 56 has a hemispherical curved surface 56a that curves to bulge forward. The inner surface of the elastic body 56 has a hemispherical curved surface 56b that curves to concave forward.

[0073] Therefore, even if the arm 41 rotates around the link shaft 40 and the direction of the load input to the elastic portion 55 changes, the load is likely to act on the elastic main body portion 56. Therefore, the elastic main body portion 56 is likely to undergo compressive elastic deformation regardless of the change in the direction of the load input to the elastic portion 55. Therefore, it is possible to prevent the biasing force of the elastic main body portion 56 from changing significantly due to the change in the direction of the load input to the elastic portion 55.

[0074] <Modifications> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0075] 2, the position of the loading platform 20 in the vertical direction may be changed, provided that the loading platform 20 is positioned above the contact points of the front wheels 32 and both rear wheels 34 with the road surface 10, for example, the general road surface 11. For example, the bottom surface 21a of the loading platform 20 may be positioned higher than the uppermost ends of the front wheels 32 and both rear wheels 34.

[0076] (Matters related to the steering shaft 30) The central axis CL1 of the steering shaft 30 in Figure 2 may extend vertically. (Matters related to the wheels) The number of front wheels 32 may be changed to more than one. The number of rear wheels 34 may be changed to three or more. If the number of front wheels 32 is changed to more than one, the number of rear wheels 34 may be changed to one.

[0077] The front wheels 32 may be driven to rotate by a motor provided outside the front wheels 32. The front wheels 32 may be driven by a power source other than a motor. The rear wheels 34 may be drive wheels that are driven to rotate by a power source, and the front wheels 32 may be driven wheels. In addition to the front wheels 32, the rear wheels 34 may be drive wheels that are driven to rotate by a power source.

[0078] The wheel diameters (diameters) of the front wheels 32 and the rear wheels 34 may be different. (Matters related to the arm 41) In each arm main body 42 in Figures 5 and 6, the front plate 43 does not necessarily have to be bent relative to the rear plate 45. Each arm main body 42 may be, for example, in the shape of a triangular plate.

[0079] In cases such as when the front wheels 32 are not driven to rotate by a motor, the front wheel axle 33 may be separated from the front wheels 32. In this case, instead of the cutouts 44, bearing holes may be formed in the front end of each arm main body 42. Portions of the front wheel axle 33 that protrude from the front wheels 32 to both sides in the direction in which the front wheel axle 33 extends may be inserted into bearing holes formed in each arm main body 42, thereby being supported by the arm main body 42. In order to insert the respective protruding portions of the front wheel axle 33 from the front wheels 32 into the bearing holes of the arm main body 42, the arm 41 may be configured so that the two arm main bodies 42 are separated.

[0080] (Matters Related to the Elastic Portion 55) An elastic body different from that used in the above embodiment may be used as the elastic portion 55. For example, a spring such as a coil spring or a leaf spring may be used as the elastic portion 55. An elastic body other than a spring may be used as the elastic portion 55.

[0081] (Other Matters) The carry cart of the present disclosure may be applied to a non-self-propelled carry cart. According to this modification, when the front wheels 32 come into contact with the step 12, the front wheels 32 can be caused to climb over the step 12 without the user having to perform an operation such as lifting the front wheels 32. This makes the carry cart CC easier to use, as it allows the user of the carry cart CC to easily climb over the step 12 even when the front wheels 32 come into contact with the step 12.

[0082] The carry cart CC may include a seat for a user to sit on or a shopping basket. The carry cart CC may include a structure for detachably attaching a shopping basket. The carry cart CC may include a structure for hanging a carrier bag, a suitcase, or other bag.

[0083] The carry cart CC may be provided with a brake mechanism for adjusting the traveling speed or stopping the travel of the carry cart CC. In this modification, the rotational speed of the front wheels 32 and / or the rear wheels 34 can be adjusted by applying a braking force to at least one of the front wheels 32 and / or the rear wheels 34 while the carry cart CC is traveling. The travel of the carry cart CC can be stopped by stopping the rotation of at least one of the front wheels 32 and / or the rear wheels 34.

[0084] The carry cart CC may be provided with a brake mechanism for keeping the carry cart CC stationary when parked. In the case of a carry cart CC with a seat, the carry cart CC may be provided with a brake mechanism for keeping the carry cart CC stationary when a user is seated on the seat.

Claims

1. A carry cart comprising: wheels configured to roll on a road surface; a loading platform located above the contact points of the wheels with the road surface; a handle shaft having a central axis extending in a direction intersecting the horizontal plane and connected to the loading platform by a connecting part; and a link member and an arm respectively provided below the connecting part, wherein the wheels comprise: front wheels supported by the handle shaft via the link member and the arm and configured to roll by rotating around the front wheel axle; and rear wheels configured to roll behind the front wheels in the direction of travel of the carry cart, wherein the carry cart is configured to travel forward in the direction of travel by the rolling of each wheel; the link member is attached to the handle shaft and has a link main body part behind the front wheel axle in the direction of travel; the arm supports the front wheel axle, and has an arm main body part supported by the link shaft behind the front wheel axle in the direction of travel so as to be rotatable up and down relative to the link main body part; An elastic part is arranged behind the arm in the direction of travel, and is configured to elastically deform as the arm rotates upward around the link shaft, and when both the front wheels and the rear wheels are in contact with the same horizontal plane, the link shaft is located behind the central axis and below the connecting part.

2. A carry cart as described in claim 1, wherein the central axis of the handle shaft is inclined relative to the vertical line so that the upper part is positioned more rearward in the direction of travel.

3. A carry cart as described in claim 1 or claim 2, further comprising a bracket attached to the link main body portion, wherein the bracket has a bracket main body portion rearward of the arm in the direction of travel, and the arm further comprises an arm attachment portion rearward of the front wheel and forward of the bracket main body in the direction of travel, and the elastic portion comprises: a first attachment portion attached to the arm attachment portion; a second attachment portion attached to the bracket main body portion; and an elastic main body portion formed of rubber so as to be elastically deformable and configured to connect the first attachment portion and the second attachment portion to each other.

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